Conical filter having bonded end flaps

ABSTRACT

Primarily a pair of substantially fan-shaped filter sheets are laid one upon another and bonded to each other at least in the proximity of their side edges to obtain a basic filter 4 adapted to form a bag having a circular opening as arc-shaped outer edges 24A, 24B of these filter sheets, wherein a pair of substantially crescent-shaped flap sheets 6 are bonded along their arc-shaped edges to said basic filter 4 along their arc-shaped outer edges 24A, 24B to obtain a filter 1 provided with a pair of pockets 8 openable downwardly of the filter 1.

FIELD OF THE INVENTION

The present invention relates to a filter particularly suitable to makecoffee or tea.

BACKGROUND ART

A conventional disposable filter used to make a cup of coffee comprisesa pair of substantially fan-shaped filter sheets laid one upon anotherand bonded to each other along their opposite side edges as well asalong their bottom edges so as to form a bag in an inverted cone-shapeas their arc-shaped free edges are spaced from each other. Such a bag isusually received by a substantially similar shaped cup used incombination with such a filter. Then, a desired quantity of coffeepowder is introduced into the bag and hot water is poured onto thecoffee powder so that coffee drips to the cup bottom.

When the known filter is used to make coffee, a quantity of coffeesoaking out through a peripheral wall of the filter inevitably flowsalong an inner wall of the foresaid cup used in combination with thefilter down to the bottom of this cup. However, coffee is sometimesunacceptably cooled by contact with this cup and must be reheated by acoffee server. This reheating is troublesome task.

Accordingly, it is a principal object of the invention to solve theforesaid problem by forming a pair of pockets adjacent the opening ofthe inverted cone-shaped filter allowing a separately prepared hanger tobe assembled in the filter.

SUMMARY OF THE INVENTION

The object see forth above is achieved, according to the invention, byan improved filter comprising a pair of filter sheets beingsubstantially identical in shape and in size, each of the filter sheetshaving a pair of side edges diverging upward and arc-shaped end edgesextending between ends of the side edges so as substantially to define afan-shape, the pair of filter sheets being laid one upon another andbonded to each other at least in the proximity of the side edges so thatthe arc-shaped end edges may form a circular opening as the filtersheets are spaced from each other, wherein substantially crescent-shapedflap sheets are bonded along their arc-shaped upper end edges to form apair of pockets openable downward from the upper end edges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a filter according to the inventionas being actually used;

FIG. 2 is a sectional view taken along a line W--W in FIG. 1;

FIG. 3 is a sectional view taken along a line X--X in FIG. 1;

FIG. 4 is a plan view of the filter as partially broken away;

FIG. 5 is a plan view showing the filter of FIG. 4 as having beendeveloped;

FIG. 6 is a perspective view showing the filter of FIG. 4 as forming anopening; and

FIG. 7 is a sectional view taken along a line Y--Y in FIG. 6.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENT

Details of a filter according to the invention will be described inreference with the accompanying drawings.

FIGS. 1, 2 and 3 respectively show a filter 1 in a perspective view asbeing actually used, and in sectional views taken along lines W--W andX--X, respectively. Referring to FIG. 1, the filter 1 is shown as hungon a hanger 2. The filter 1 is shaped in an inverted triangle as viewedin the sectional view taken along the line W--W and shaped in atrapezoid having its bottom side being shorter than its top side, andcomprises a filter body 4 with its top side forming a circular opening 3and flap sheets 6 each having an upper portion bonded the filter body 4along a partial peripheral edge of the opening 3 and a lower portiondefining a free edge 5 so that a pocket 8 opening downwardly of thefilter 1 may be formed between a peripheral wall of the filter body 4and the respective flap sheets 6. The hanger 2 is made of stainlesssteel wire rod and comprises an annular portion 11, a grip portion 12formed by a part of the annular portion 11 extending outward, and astopper portion 13 extending outward from the annular portion 11 in thedirection opposite to that in which the grip portion 12 extends. FIG. 1shows the grip portion 12 and the stopper portion 13 placed on an edgeof a coffee cup 15 indicated by an imaginary line. Coffee powder 16 isintroduced into a space defined by the filter 1 through the opening 3and then an appropriate quantity of hot water is poured onto the coffeepowder. Consequently, coffee drips into the cup 15.

FIGS. 4 and 5 are a plan view of the filter 1 as partially broken awayand a plan view showing an original filter sheet 21 and the flap sheets6 in a state after the filter 1 has been developed, respectively. Theoriginal filter sheet 21 comprises a pair of substantially fan-shapedsections 21A, 21B which are vertically symmetric with respect to acenter line Z--Z, the sections 21A, 21B being respectively defined byside edges 22A, 23A and 22B, 23B progressively diverging from eachother, respectively, as they become more distant from the center lineZ--Z, and arc-shaped upper end edges am:tending between ends of the sideedges 22A and 23A and between ends of the side edges 22B and 23B,respectively. Between a lower end edge of the side edges 22A, 22B and alower end edge of the side edges 23A, 23B, the center line Z--Z definesa fold line 27 as will be described later. The flap sheets 6 aresubstantially crescent-shaped having their arcs 25 bonded along theirouter edges 24A, 24B to the associated fan-shaped sections 21A, 21B,respectively, and their chords 26 remaining free so that the originalfilter sheet 21 may cooperate with the respective flap sheets 6 to formthe pockets 8 opening toward the center line Z--Z. The original filtersheet 21 is folded along the fold line 27 in two with the flap sheets 6lying inside and these two halves are inseparably bonded to each otherin the proximity of the side edges 22A, 22B and 23A, 23B lying one uponanother, respectively, and thereby the filter 1 of FIG. 4 is obtained.

FIGS. 6 and 7 show the filter 1 with the outer edges 24A, 24B spacedfrom each other to form the opening 3A in a perspective view and in asectional view taken along a line Y--Y, respectively. It should beunderstood that FIG. 7 includes also a perspective view of the hanger 2in combination with the perspective view of the filter 1 for betterunderstanding of the manner in which the hanger 2 is assembled into thefilter 1. The outer edges 24A, 24B of the filter 1 shown by FIG. 4 asbeing in a flat state may be spaced from each other in a direction asindicated by arrows A to form a bag having a pair of end surfaces eachshaped in an inverted triangle and the pockets 8 defined between thefilter body 4 and the respective flap sheets 6 so as to open downwardly.The other pair of end surfaces which are orthogonal to the line Y--Y andcontaining the center line Z--Z (See FIG. 5) are shaped in trapezoidshaving their bottom sides defined by the fold line 22.

In actual use of the filter 1, the annular portion 11 of the hanger 2 isinserted into the pockets 8 through the opening 3A in a direction asindicated by arrows B, as shown by FIG. 7. Then, the bottom of thefilter body 4 is forced up in the direction indicated by arrows D beyonda plane defined by the opening 3A as shown by imaginary lines 4A to turnthe filter 1 over. The filter 1 is then in the state as shown by FIGS. 1and 2 but this is an upside down state which is unsuitable forimmediately use. To be ready for use, the manner of holding the hanger 2is changed so as to make the opening 3A overlie the remainder. Theopening before turning over is designated by reference numeral 3A andthe opening after turning over is designated by 3. Once the pockets 8have been formed outside the filter 1 as a result of the turning over,the filter body 4 and the respective flap sheets 6 are relatively movedclose to each other under a load of hot water poured onto the coffeepowder supported by the filter 1 and thus the filter 1 is reliablyprevented from falling off from the hanger 2.

For the invention, the filter body 4 and the flap sheets 6 may be madeof any suitable sheets usually employed as material for filters such aswoven fabric, nonwoven fabric or filter paper and these may be bonded toone another by use of adhesive or embossing. However, for the filter 1destined to be used to make coffee or tea, it is preferred to usenonwoven fabric of heat-sealable synthetic fibers and to heat seal it inorder to obtain the filter 1 in view of an apprehension that use ofadhesive might deteriorate taste of coffee or tea. As an example ofpreferable nonwoven fabric is of a composite fiber comprisingpolyethylene and polypropyrene having a weight per unit area of20-70g/m², more preferably of 30-50g/m². In this case, the filter 1 issuitable to be used as disposable filter, since such filter 1 isadvantageous in strength, material cost and manufacturing cost.

While the filter 1 of the invention has been described hereinabove asused to make coffee, the filter 1 can find many other applications, forexample, for scooping up bits of deep-fried Tempura batter from fryingoil. According to the embodiment as shown, the pockets 8 are providedinside the filter 1 and, after the hanger 2 has been assembled into thefilter 1, the filter 1 is turned over, from the view point that suchprocedure facilitates the hanger 2 to be inserted into the pockets 8.However, if such convenience is not required, the pockets 8 can beinitially provided on the outer side of the filter 1. Moreover, whilethe filter body 4 substantially comprises a pair of original filtersheets and, according to the embodiment as shown, a single originalfilter sheet 21 being vertically symmetric with respect to the centerline Z--Z is folded in two along the fold line 27, it is also possibleto prepare separate sheets as the sections 21A, 21B of the originalfilter sheet 21, to lay these separate sheets one upon another and tobond them together along their portions corresponding to the center lineZ--Z. It is also possible to configure the separately prepared sheets21A, 21B so that the lower ends of side edges 22A, 23A as well as thelower ends of the side edges 22B, 23B intersect each other,respectively, i.e., a length of the zone corresponding to the centerline Z--Z become zero. In this case, the filter 1 will present aninverted cone-shape and its end surface as viewed in a diametricaldirection will be shaped an inverted triangle. While the flap sheets 6are preferably of liquid-permeable filter sheets, they may be ofliquid-impermeable sheets.

INDUSTRIAL UTILITY

The filter constructed as has been described above is used with thehanger comprising the annular portion having its diameter slightlysmaller than that of the filter opening and the grip portion. Uponinsertion of the annular portion into the pair of pockets formed on theouter side by the filter sheet and the flap sheets, the filter is hungdown with its pockets being supported by the hanger and forms the baghaving its end surface shaped in the inverted triangle or the trapezoidhaving its bottom side being shorter than its top side as viewed in thediametrical direction. The filter sheet and the flap sheets arerelatively moved close to each other under a load of hot water pouredinto the filter and thereby reliably prevented from falling off from thehanger. When hot water is poured into the filter thus suspended by thehanger to make coffee, hot water is not easily cooled because there isneither cup nor any other means with which hot water is contact.

The filter of the invention can be also used to scoop up floating matterfrom liquid contained by a container.

The filter may be advantageously made of filter paper or nonwoven fabricto be used as disposable filter.

What is claimed is:
 1. A filter comprising a pair of substantiallyidentical filter sheets, each having a pair of upwardly diverging sideedges and an arc-shaped upper end edge extending between ends of saidside edges so as substantially to define a fan-shape, said pair offilter sheets being laid one upon another and bonded to each other atleast in the proximity of said side edges so that said arc-shaped upperend edges may form a circular opening as the filter sheets are spacedfrom each other; and:a pair of substantially crescent-shaped flap sheetsbonded along arc-shaped edges thereof to the respective filter sheets toform a pair of pockets openable downward from said upper end edges.
 2. Afilter according to claim 1, wherein, in a collapsed state of saidfilter sheets prior to use, said pockets are formed on an inner side ofsaid filter.
 3. A filter according to claim 1, wherein said filtersheets and said flap sheets are made from nonwoven fabric ofheat-sealable fibers and bonding of these members are achieved byheat-sealing said nonwoven fabric.
 4. A filter according to claim 1,wherein said filter sheets are formed without any openings other thansaid circular opening.
 5. A filter according to claim 1, wherein theupper edges only of the flap sheets are attached to said filter sheets.6. A filter according to claim 1, wherein each flap sheet is coextensivewith a major portion of the associated arc-shaped upper end edge.
 7. Afilter comprising a pair of filter sheets each having a pair of upwardlydiverging side edges and an upper end edge extending between ends ofsaid side edges, said pair of filter sheets being laid one upon anotherand bonded to each other at least in the proximity of said side edges sothat said upper end edges may form an opening as the filter sheets arespaced from each other; anda pair of flap sheets respectively attachedalong at least one edge thereof to the respective filter sheets alongsaid upper end edges to form a pair of pockets openable downward fromsaid upper end edges, wherein, in a collapsed state of said filtersheets prior to use, said pockets are formed on a inner side of saidfilter; wherein the upper edges only of the flap sheets are attached tosaid filter sheets.
 8. A filter comprising a pair of filter sheets eachhaving a pair of upwardly diverging side edges and an upper end edgeextending between ends of said side edges, said pair of filter sheetsbeing laid one upon another and bonded to each other at least in theproximity of said side edges so that said upper end edges may form anopening as the filter sheets are spaced from each other; anda pair offlap sheets respectively attached along at least one edge thereof to therespective filter sheets along said upper end edges to form a pair ofpockets openable downward from said upper end edges, wherein each flapsheet is co-extensive with a major portion of said upper end edge of theassociated filter sheet; wherein the upper edges only of the flap sheetsare attached to said filter sheets.